Test: Properties of Metals, Simple Stress Strain & Elastic Constants - 2 - Civil Engineering (CE) MCQ

• Definition: St. Venant's principle states that stress conditions approach uniformly as the distance from the point of application of the load increases.


• Uniform Stress Distribution: This principle implies that within a certain distance from the applied load, the stress distribution in a material will be uniform.


• Equal Stress: The principle also suggests that as the distance from the load increases, the deformations of all materials for a given loading become equal.


• Relieving Stresses: Contrary to option D, St. Venant's principle does not imply that stresses in a loaded member tend to relieve after a point of time. Instead, it focuses on the uniformity of stress distribution.


• Application: Engineers often use St. Venant's principle to simplify stress analysis in structural mechanics, allowing for easier calculations and predictions of material behavior under loads.

Notched bar test- Impact Strength of a Material
Indentation Test- Hardness of a Material
The machinability rating is determined by measuring the weighted averages of the normal cutting speed, surface finish, and tool life for each material.
Salt Spray/Fog Test- Corrosion resistance of the material.

• Creep Test: The creep test is a type of test used to measure the behavior of materials under a constant load over an extended period of time.


• Type of Stress: In the creep test, uniaxial tension stress is applied to the specimen.


• Uniaxial Tension: Uniaxial tension stress refers to the stress applied in a single direction, causing the specimen to elongate.


• Behavior of Materials: By subjecting the specimen to uniaxial tension stress in the creep test, researchers can observe how the material deforms over time and analyze its creep behavior.


• Creep Behavior: Creep behavior is the tendency of a material to deform slowly under a constant load, which is important to understand in various engineering applications.

Since the bar is free to expand, no stresses will be developed in the bar.

• Explanation of Cup-and-Cone Fracture: Cup-and-cone fracture is a type of fracture that occurs in ductile materials when subjected to tensile stress.


• Characteristics of Cup-and-Cone Fracture: This type of fracture is characterized by the formation of a cup-shaped cavity on one side of the fracture surface and a cone-shaped projection on the other side.


• Reason for Occurrence: Cup-and-cone type fracture occurs in round specimens of ductile metals because the stress distribution is symmetrical around the circumference of the specimen.


• Explanation of Other Options:
  
  
  
  • Cast iron typically exhibits a brittle fracture.
  
  
  • Tough steel is more likely to exhibit a ductile fracture rather than a cup-and-cone fracture.
  
  
  • Soft brass is also more likely to exhibit a ductile fracture rather than a cup-and-cone fracture.
  
  
  
  

Brittle materials have very little or no plastic deformation before they fracture, which means they do not exhibit a distinct yield point (unlike ductile materials). They tend to fail suddenly when they reach their ultimate stress rather than yielding or undergoing plastic deformation.

• Ultimate Stress (d): This is the maximum stress that a material can withstand before failure. Since brittle materials fracture at this point without significant plastic deformation, the factor of safety for brittle materials is based on the ultimate stress to ensure they do not reach the stress level at which they would break.

 = 0.4664 x 10⁵ MPa